The influence of non-radiative relaxation on the room-temperature phosphorescence of metalloporphyrin

Abstract

The room-temperature phosphorescence (RTP) of metalloporphyrins, induced by the heavy atom effect (HAE), has been widely concerned in many fields, and the intense emission of RTP is highly desired. The phosphorescent transition rate ([Formula: see text] has been used to quantitatively characterize the HAE’s intrinsic nature. However, the phosphorescent intensity was not determined by [Formula: see text] alone, non-phosphorescent transition ([Formula: see text] induced by surrounding factors was also involved. In this study, the influence of [Formula: see text] on the RTP of palladium octaethylporphyrin (PdOEP), platinum octaethylporphyrin (PtOEP), and platinum tetraphenylporphyrin (PtTPP) was studied. The effect of [Formula: see text] can be quantitatively described by an introduced parameter [Formula: see text], which was defined as [Formula: see text] = [Formula: see text]/([Formula: see text]. The method is proposed for determining the [Formula: see text] of PdOEP, PtOEP, and PtTPP by the UV-visible absorption spectra, luminescence spectra, and phosphorescence dynamic curves. Our research provides a way to understand the effect of knP on the RTP, and may benefit the development and optimization of metalloporphyrins aiming at intense RTP.